Can supplements help psoriasis and psoriatic arthritis?

Visit TalkPsoriasis.org and you'll find hundreds of people who are trying everything from fish oil and vitamin D to more exotic remedies like milk thistle to improve their psoriatic symptoms.

It's easy to understand why his patients are interested in using supplements, but Dr. Wilson Liao, associate professor of dermatology at University of California-San Francisco urges caution.

"I encourage patients to work with me when they want to try something, to keep a journal to log what and how much they're taking and what effects they experience," he said. "Then we can review it together and see how well something's working."

Supplements and vitamins, while natural, can have potent effects and cause serious problems, Liao said.

"St. John's wort, for example, can interfere with several medications, including cyclosporine, which is used to treat psoriasis, he said. "Supplements aren't regulated by the FDA, which means you don't really know what dosage or quality you're getting, or what problems could occur. Always check with your doctor before taking anything."

That lack of government regulation allows manufacturers to tout health claims that aren't backed up by science, said Dr. Nancy Anderson, professor of dermatology at Loma Linda University in California. She said it is critical to get a doctor's input before taking any supplement, including vitamins, minerals and herbs.

"Some may have the potential to worsen your condition or cause other issues," she said. "Vitamin E, for example, can increase bleeding, which can be a problem if you're undergoing surgery, or even an in-office cosmetic procedure."

Here, we review the evidence for some better-studied vitamins and supplements.

Fish oil/omega-3s

Oils from cold-water fish show the most promise for improving symptoms in psoriasis among the four possibilities studied by Liao and his dermatology group, which published an evidence-based review in September in the Journal of the American Academy of Dermatology.

"The findings make intuitive sense, as we know the omega-3s in fish oil reduce inflammation by opposing an inflammation-causing molecule called leukotriene B4," Liao said.

He and his colleagues reviewed 15 trials of fish oil use in psoriasis; 12 found some benefit, typically a moderate improvement in skinredness, plaque thickness and scale amount. Several studies found omega-3s seemed to boost benefits of traditional psoriasis therapies, including UVB therapy and oral retinoids.

Patients in the studies took different amounts of fish oil — with some taking very high amounts — for periods varying from six weeks to six months. Fish oil was found to be most effective in people taking it for three months or more.

Anderson, who often recommends fish oil to her psoriasis patients for its potential to benefit both skin and heart health, usually suggests starting at 1,000 milligrams a day, as higher doses may cause stomachupset. Fish oil quality varies, so ask your doctor to recommend a brand.

Vitamin D

People with psoriatic disease often have low-levels of vitamin D, which helps regulate immune system function. A 2012 study in the British Journal of Dermatology found that 57 percent of people with psoriasis had vitamin D deficiency, a figure that rose to 80 percent in winter months. Anderson checks vitamin D levels in most of her psoriasis patients and said the practice is becoming more common.

In people who aren't vitamin D-deficient, the evidence for supplementation is mixed, said Liao.

"Six of the seven studies we looked at found an improvement in skin symptoms with vitamin D supplementation — but the one trial that didn't show benefit was also the only randomized, controlled trial," the most reliable kind of clinical research, she said. "We need more study to know if there's really a benefit."

While the benefit is unknown, the downside is not. Too much vitamin D can cause excess blood calcium and kidney stones, and Anderson cautions against doubling or tripling up on recommended doses of vitamins and supplements "because they're natural."

Vitamin B12 and selenium

There are very few studies testing vitamin B12 and selenium supplementation in people with psoriasis, and the ones that have been conducted have produced contradictory results, said Liao. Anderson said she advises her patients with psoriasis to take a good multivitamin, one that contains selenium and zinc, which have been shown to be good for the skin and other organs.

Other options

Possibilities being tested in the lab, used by naturopathic doctors or tried by psoriasis patients, include the spice turmeric, which is being studied at MD Anderson Cancer Center at the University of Texas for its anti-inflammatory and antioxidant properties; bitter melon, a plant used in traditional Asian and African medicine; resveratrol, an antioxidant plant compound; and probiotics, gut-friendly bacteria that may benefit immune system function and reduce inflammation.

However, approach any potential vitamins and supplements with a dose of skepticism, and always check with your doctor before beginning a new regimen.

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